Just go into heroic Botanica and tank the 1st patrol, or tank the Bog Overlord in heroic Steamvaults. It might cost you 2g, but at least you know where you stand in regards to tanking viability

Heroic slave pens is supposed to be the easiest, yet with 67% mitigation I get smacked around for 800-1000 by trash mobs. Pain!

Defenders... waah, have to ask frost mage to kite one fella, cos if I tank two I get hit for around 3k each time, no way healer can keep up. While kiting, if one spell reflect up, suddenly the mage frost bolted himself and then he gets one-shotted by the defender.

The ideal group setup here seems to be warrior, rogue, mage x2 and shaman. The rogue is great simply because of the stun on MC mobs and crippling poison on defenders.